Speaker drivers (e.g., electrodynamic speakers) are electromechanical devices used to generate sound and are commonly found in devices such as loudspeakers, televisions, and the like. Examples of speaker drivers include but are not limited to woofers, subwoofers, tweeters, super-tweeters, and rotary woofers. Speaker drivers generally comprise a diaphragm (e.g., speaker cone) mounted on a suspension system (e.g., spider, frame, etc.). A voice coil (e.g., a coil of insulated wire) is attached to the neck of the diaphragm. A fixed magnet sandwiched between a front plate and back plate is positioned in close proximity to the voice coil. Other components of speaker drivers may include a dust cap, etc.
When the electric current is applied to the voice coil (e.g., via electrical wires), a magnetic field is generated. The magnetic field interacts with the permanent magnetic field by the front and back plate attached to the fixed magnet. Depending on the polarity of the electric current, the voice coil will respond accordingly moving either back or forth causing the diaphragm (e.g., speaker cone) to move in the same fashion (e.g., forward-backward), which produces pressure differentials that travel as sound waves.
Speaker drivers are generally mounted in enclosures (e.g., box-type speaker enclosures). The sound waves of the speaker drivers thus ultimately interact with the surrounding walls of the enclosures. This can be problematic in some cases. For example, as the diaphragm (e.g., speaker cone) moves back and forth, back waves may first hit the enclosure walls and then be reflected by the enclosure walls. The reflected waves then either hit the enclosure walls again or hit the speaker cone, which can cause sound coloration and distortion (e.g., internal interaction). In some cases, the front sound waves generated by the diaphragm (e.g., speaker cone) can be reflected by the front panel, which causes smearing (e.g., external interaction).
The present invention features a speaker enclosure (e.g., transmission line enclosure) comprising an outer main enclosure and an inner sub enclosure (e.g., an even number of inner sub enclosures). The main enclosure and sub enclosure are arranged such that the back waves generated by the speaker cone can move more freely and the total traveling distance for the back waves from the speaker cone to the exit port is equal to about ¼ wavelength of the tuned frequency. In some embodiments, for example to increase bass output, a passive radiator can be installed at the exit port. Passive radiators are well known to one of ordinary skill in the art. The speaker enclosure of the present invention can be constructed in a variety of configurations, for example tube, column, box, space, and/or the like.
Without wishing to limit the present invention to any theory or mechanism, it is believed that the speaker enclosure of the present invention is advantageous because the back waves generated by the speaker cone movement may move freely due to the internal structure of the speaker enclosure. Thus, common acoustic problems such as sound reflection, diffraction, coloration, distortion, and the like may be reduced as compared to regular box-type speakers. High-quality sound can be produced from the speaker enclosures of the present invention. Also, the speaker enclosure may be less expensive to construct as compared to other types of speaker enclosures. High quality sound can be reproduced by the speaker enclosure of the present invention because commonly found acoustic problems in standard box-type enclosures may be minimized in the present invention. The speaker enclosure can be produced in a variety of configurations. In some embodiments, a form of a jacket is used for visually enhanced presentation or structurally improved speaker driver installation.
Any feature or combination of features described herein are included within the scope of the present invention provided that the features included in any such combination are not mutually inconsistent as will be apparent from the context, this specification, and the knowledge of one of ordinary skill in the art. Additional advantages and aspects of the present invention are apparent in the following detailed description and claims.